Vascular targeting is a promising new strategy for detecting and treating solid tumors but a thorough assessment of the localization and processing of potential tumor targeting probes by tumor vessels is key to prioritizing candidate targets for future basic and clinical study. Imaging in this core will range from the whole body level to the tissue/cell level to subcellular elements and will include both static "snap shots" as well as dynamic, real-time, continuous visualization of probe targeting and processing. The Imaging Core Facility will provide the necessary equipment and expertise to enable Program Project Investigators to obtain key information about their most promising candidates quickly and in a cost-effective manner. The services provided by the core include: 1) Cutting of tissue sections of human, rat, and mouse samples for light, fluorescence, and electron microscopy; 2) Providing assistance, and/or directly processing, rat and mouse tissue/tumors for localization of targets and targeting probes and evaluation of tissue damage after treatment; 3) Providing supervised or direct assistance in operating the imaging equipment (SPECT camera and light, fluorescence, deconvolution, and electron microscopes); 4) Providing sound expert advise to all PPG participants in performing all aspects of imaging necessary for each of the projects and to assist in imaging data analysis and interpretation; and 5) Producing the probes necessary for the imaging studies, including fluorophore and colloidal gold conjugations, biotinylations, and radioactive labeling. The Imaging Core will be directed by Dr. Jan Schnitzer (Program Director), who has over 20 years experience in all aspects of digital and microscopic imaging, and will be dedicated to providing all participating scientists with an easily accessible, user-friendly, and state-of-the-art facility for imaging the targeting, processing, and efficacy of tumor-homing probes.